NATO (searchdefense ministers are testing their response to sudden threats from terrorism and weapons of mass destruction during an unprecedented crisis management exercise.

Full details of the exercise were kept secret ahead of its start, but diplomats said it would, in part, involve a crisis in the Middle East set in 2007 with Westerners trapped on a fictional Red Sea island.

The exercise Wednesday at Schriever Air Force Base (searchoutside this Rocky Mountain city will involve ministers and top military brass from the 19 NATO allies and seven east European nations due to join the alliance in May.

It is designed to evaluate national crisis procedures (search), some of which are criticized as too unwieldy to handle modern day threats. The exercise is also intended to demonstrate the potential of the elite rapid response force that NATO is putting together.

"The task today is to be able to deal with problems in hours or days, not weeks or months or years, and the NATO Response Force is going to be designed to do exactly that," Defense Secretary Donald H. Rumsfeld told reporters Tuesday.

First units of the force are to be activated next week. It's scheduled to reach full strength of 20,000 in 2006.

Later sessions of the two-day NATO meeting will deal with current alliance missions in Afghanistan and Bosnia, where European allies are offering to play a larger peacekeeping role -- an offer that would free up U.S. troops stretched by the Iraq occupation.

On Monday, NATO asked the United Nations for permission to expand the alliance's peacekeeping mission in Afghanistan, which is currently limited to the capital Kabul.

Diplomats at NATO headquarters say the plans could involve 2,000 to 10,000 more troops moving out into provincial cities. The current NATO-led International Security Assistance Force has 5,000 mostly German and Canadian troops.

The NATO mission, which operates under a U.N. mandate, is separate from the U.S.-led combat force of 11,500 fighting Al Qaeda and the Taliban in the countryside.

Although the allies agree to expand the force, NATO Secretary General Lord Robertson has acknowledged a shortage of properly trained and equipped European troops could limit the scope of such an expanded operation.

Robertson is expected to press European ministers to modernize their armed forces, making more available for far flung, combat or peacekeeping missions.

European Union ministers offered Saturday to take charge next year of the peacekeeping mission in Bosnia that NATO has run since 1995.

U.S. officials have expressed reservations about an early handover to the Europeans, fearing the EU's fledgling defense arm is ill-prepared to handle Bosnia's ethnic tensions, organized crime and the hunt for war crime suspects.

However, diplomats say Washington is warming to the idea, which could release the 1,500 U.S. troops who make up around 10 percent of the NATO force in Bosnia.